How to seal a Shower Drain for inspection

[lzicc]

Did you every see those punching balloons that have the rubber band on the end? I though about sticking that down past the threads, into the 2" pipe then blowing up with the compressor to seal it off. Those balloons are pretty heavy and should be able to seal it off or am I being silly?

 

[Damifino]

Here is what I use. It's made by Rectorseal and is called a 2"twister, as shown in with it inserted in drain, it passes through drain ans has a o-ring seal. When you tighten the orange knob there are teeth that expand to grip the pipe.

Edit to show out of drain